While organizations worldwide are beginning to acknowledge their need to adopt IPv6, most are still struggling to define a workable strategy around it. In this article we analyze the challenges that companies will face when migrating to IPv6 and ways to overcome them along with migration strategies.

Introduction

IPv6 was developed in the mid-1990 by the Internet Engineering Task Force (IETF). It was primarily engineered to remove the fundamental address space limitation of IPv4. IPv6 uses 128 bits for IP addresses versus 32 bits in IPv4, thus providing a practically unlimited address space that enables any device to have a unique IP address. Thus the need for network address translation (NAT) as a means to cope with limited address space is eliminated, although today NATing also is viewed as a component of network security and is not expected to go away any soon.

No doubt, IPv6 improves routing efficiency through better address aggregation resulting in smaller Internet routing tables. It also provides better end-to-end security, improved QoS support, and increased mobility. Governments and organizations in Asia and Japan are further along the migration path to IPv6 due to limited IPv4 address allocations. Organizations conducting business in these geographies have to support IPv6 communication.

Migration Challenges

The problem is that the entire world will not switch to IPv6 at the same time, nor will many organizations be able to simply flip a switch and decide that all applications and all equipment will suddenly be IPv6 instead of IPv4. What organizations need is a smart migration plan and tools to help provide an orderly transition between the two standards. The other challenge with the migration is that the production environment downtime should be restricted to minimal possible. There are several challenges associated with a transition to IPv6, some of these can be summarized as:

Ensuring the network has the same reachability and isolation characteristics as before, i.e., communication patterns are preserved

Ensuring the previous level of security is maintained

Ensuring network and application performance remains unaffected

Ensuring IPv4 and IPv6 can co-exist

Migration Strategies

No doubt that the migration from IPv4 to IPv6 will take time and resources both on part of organizations and their service providers. IPv6 is not only a network infrastructure feature but it also affects the entire IT infrastructure. It extends from server to clients, from edge to core, from OS to applications. Careful planning and assessment is required to make the migration.

Dual Stack Approach (IPv4 & IPv6 Together)

The dual-stack implementation is a common transitional mechanism where all devices (workstations, servers, routers, etc.) support both versions – IPv4 and IPv6. The applications and the network can communicate using either version.

This transitional mechanism is relatively easy to implement. Both protocols co-exist and hence, there is no problem supporting older and newer applications that use IPv4 and IPv6 respectively. The disadvantage of this approach is that the devices have to support both versions and they need extra processing power (memory, CPU etc.) to handle both protocols.

Tunnel Approach (IPv6 In IPv4)

Tunneling uses encapsulation to carry IPv6 traffic in IPv4 packets and vice versa. This allows for a partial transition where portions of the network can migrate to IPv6 while the rest of the network remains in its original state. The advantage of tunnels is that you can reuse the existing infrastructure in situations where old devices do not have enough processing power to support both protocols or you are not ready or financially able to upgrade. The disadvantage of tunneling is that it involves tedious configuration. Tunnel endpoints need extra processing power to handle encapsulation and decapsulation. Tunnels can create routing inefficiencies if they are not configured to match the underlying routing topology. Tunnels also introduce security issues, as packets that were previously visible are now encapsulated. Troubleshooting within the tunnel is difficult due to the lack of visibility into the end-to-end traffic paths.

Translation Approach

Translation lets you convert packets from one protocol to another. The advantage of this approach is that it allows for communication between devices supporting any version. However the disadvantage is that the translator has to read every packet header and this requires extra processing power. Configuration of the translator is tedious. The translator also becomes a single point of failure.

Migration Scenarios

There are two possible scenarios for a smooth, controlled migration strategy.
Organizations will find it easier to migrate servers (applications) first to IPv6 than client devices. The reason being that the servers are completely under an organization’s control whereas the devices may or may not be. For migrating servers, the gateway appliance is placed between the servers and the clients. Next, the IPv6-capable server network is added to the appliance/gateway. The result is that the network will have IPv4 on the front/client side of appliance, and both an IPv4 and IPv6 network behind it.

Once the IPv6 network is established, the servers can be moved over from the IPv4 network. Anticipating that in future all client devices will be IPv6-based, it is imperative for organizations to ensure that their infrastructure and applications are IPv6 capable.

To Conclude…

The migration of an existing IPv4 infrastructure to IPv6 will be one of the most demanding challenges facing IT organizations in the years to come. This is not because of the inherent complexities of the migration, but due to the universal reach of IP and dependency of today’s enterprises on the operation of the network. The transition to IPv6 will require planning and likely some degree of support for both protocols during the transition period. As noted by those responsible for managing Internet addresses, it is only a matter of time before IPv4 is no longer viable. Early planning will help ensure the transition is smooth with minimum impact on business operations

Author : Jayabalan Subramanian

Jayabalan is the Chief Technology Officer and co-founder of Netmagic Solutions Pvt. Ltd. He is recognized in the Industry as an expert on Internetworking and has consulted with leading organizations, including BAFL, BPL, Bharti, Worldtel, and Hathway Internet, among others.